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Development Main Results Current activities

Scanning Probe Microscopy and Nanoelectronics Laboratory was established at Physical Department, Lomonosov Moscow State University in 1986 by Prof. V.I. Panov.

Since the founding of laboratory in 1986 main interests of its staff were aimed at the development of instrumentation of scanning probe microscopy, as well as their application to study the properties of the surface and surface nanostructures..

For the period of laboratory existence the staff members have been developed and established various types of scanning probe microscopes (tunnel, atomic force, optical near-field, etc.). Mile stones are:


1988
  • The first commercial STM/STS device in Russia was designed. STM/STS microscopes possess atomic resolution due to the original design of mechanical and electronic units.
1988
  • The method for tungsten (W) STM tips electrochemical step etching was patented.
1989
  • The first Russian commercial AFM device with tunnel displacement sensor was designed.
1993
  • The ultrahigh vacuum plant (base pressure is order 10^(-8) Pa) for surface investigation by LEED and STM methods have been designed.
1996
  • Low Temperature STM with crystal cleavage mechanism capable to work in high magnetic fields was presented.
1997
  • One of the first experimental group in Russia started investigations by SNOM technique.
2000
  • Design and development of commercial Scanning Near-Field Optical Microscope. The microscope has two scanning modules and allows working in 11 optical modes.
2005
  • A mechanism for UHV cleavage of crystal specimens for the use with STM has been suggested and developed for Omicron Multi Probe UHV System.
2006
  • Compact LT STM with sample cleavage mechanism for work in transport Dewar vessel was designed.


Using developed in the laboratory facilities and unique methods of measurement its staff has conducted the extensive research in physics of surface and surface nanostructures. Among them, you can distinguish the following key results:

  • Hydrogenation process of palladium surface was studied in controllable gas environment by means of  STM/STS.
  • STM tip induced conductivity and two-dimensional conductivity were discovered in thin organic Langmuir-Blodgett films demonstrating important role played by collective effects even in room temperature STM experiment
  • Dimensional quantization effects were observed on nanometer size surface defects as well as interference between surface charge superstructures originating from neighboring defects.
  • Resonance tunneling trough localized levels of individual impurity atom was observed, resulting in switching on/off of the atom on the STM images at different tunneling bias voltage.
  • Charge effects in STM tunneling junction were discovered at low temperature, when relaxation rate of non-equilibrium electrons is comparable with the tunneling rate and charge accumulation can occur on the localized states in tunneling junction area.
  • Complicated charge screening known as Friedel oscillations was observed at low temperature in vicinity of individual impurity atom on semiconductor surface, in which case the sequence of dark/bright rings surround defect on the STM image.
  • Individual impurity atoms interaction mediated by Coulomb interaction between non-equilibrium charges was discovered at low temperature on semiconductor surface, resulting in switching on/off of atoms on STM image twice, when changing tunneling bias from negative to positive value.
  • Manifestation of Coulomb singularity effect in STM/STS experiments was observed for individual impurity atom on semiconductor surface.
  • Light induced conformational transformations of the naphthacenequinone (NQ) molecules are observed by scanning tunneling microscopy.
  • Two new Au-induced reconstructed phases on the GaN (0001) surface have been found out. The commensurate c(2x12) structure (-phase) demonstrates properties of 1D system whereas the incommensurate -phase looks similar to disordered 2D system.
  • A temperature-dependent scanning tunneling microscopy study of Na adsorption on the Si(111)-(7x7) surface by cooling the surface from room temperature to 80 K has been carried out.
  • The quasicubic Bi{012} film formed in the initial stage of the bismuth deposition on the Si(111)-7x7 has been studied. Results of our STM experiments show that paired-layer Bi{012} film grows on top of the initially formed wetting layer, with the Si-7x7 lattice preserved underneath.
  • STM investigation of Ag adsorption on the Si(110) surface has been carried out. Two types of surface reconstructions ("16x2" and 4x1) have been observed.
  • Surface morphology and controllable growth of C60 films on a semimetallic Bi(001)/Si(111) template surface were studied under ultra-high vacuum conditions using scanning tunneling microscopy.
  • The nature of fundamental 1/f^ noise has been clarified by means of UHV STM. It was found out that the power law exponent of 1/f^ noise in STM investigations of tunneling current noise spectra depends on the presence and kind of impurity atoms in the tunneling junction area.
  • Low temperature UHV STM/STS observation of ring-like surface electronic features in local density of states that appear around Co metal islands deposited on a clean surface of cleaved p-type InAs(110) crystals.
  • 3D Mapping of Local Spatial Distribution of Electromagnetic Field Intensity Near the Nanocylinders by means of Scanning Near-Field Microscopy.
  • Polarization nanostructures properties analysis similar to that of the conventional domain imaging with the Faraday effect with high spatial optical resolution by means of SNOM.
  • SNOM observation of different polarized components of electromagnetic field near nanoaperture.
  • The optical NanoVortexes were found out in the electromagnetic field spatial distribution, formed with a polymeric nanocylinder, covered with 25-nm film of AuPd alloy.
  • Peculiarities of tunneling current conductivity spectra formed by the electron-phonon interaction in the case of strong interaction between adsorbed atom atom or molecule and substrate surface are studied theoretically.
  • Selfconsistent theory of tunneling processes in low dimensional nanostructures and tunneling nanocontacts which take into account finite time of relaxation of nonequilibrium cariers is created. This theory gave an opportunity to describe experimental results in scanning tunneling microscopy. It also predicted new effects in semiconductor and superconductive nanostructures.
  • The theoretical model describing the 1/f fluctuations of tunneling current in the presence of localized states has been considered. Spectral dependencies demonstrate that taking into account the Coulomb interaction between localized states and electrons in the leads of tunneling contact, leads to singular behavior of low frequency component of tunneling current spectra depending on frequency in the range of zero frequency.


Presently at the Laboratory of Probe Microscopy and Nanoelectronics the work on the improvement of microscopy techniques necessary to study the surface and surface nanostructures in ultra high vacuum, at low temperatures, in high magnetic fields, and under optical excitation of nanostructures is conducting.

Research continues to examine the possibility of creating nanoelectronic devices using probe microscopy. To explain experimentally observed effects theoretically, Keldysh diagram thechnique for Green's function method is widely used. Electronic properties of surface nanostructures are modeled using ab initio calculations based on density functional theory.


Current activities in our laboratory:

Experimental branch:

  • Ultra High Vacuum STM/STS on Semiconductors (Si, Ge, InAs, GaAs etc.).

  • Low Temperature (down to 4.2K) STM/STS on Semiconductors.

  • Ultra High Vacuum Low Temperature (down to 4.5K) STM/STS on Semiconductors and Metal surface.

  • Ultra High Vacuum Low Temperature STM/STS on Magnetic Nanostructures.

  • Scanning Near-Field Optical Microscopy investigation of light interaction with surface nanostructures.

  • Atomic Force Microscopy techniques – used as a powerful tool for nanostructures’ geometry characterization.

Theoretical investigation:

  • The influence of localized states in tunneling junction area on local density of electronic states and small tunneling characteristics.

  • First principal calculation of the nanostructures electronic properties using Density Functional Theory (DFT).




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